1. Field of the Invention
The present invention relates to a light emitting diode (LED) package. More particularly, the present invention relates to an LED package having a plurality of LED chips electrically isolated from one another.
2. Description of Related Art
In an LED package, group III-V elements serve as main materials of a light emitting layer, and a current is applied to the light emitting layer. Through combination of electrons and electron holes, redundant energy is released in a form of light, thus achieving a light emitting effect. In comparison with conventional light emission through heating or discharging, the light emitted from the LED package is a type of cold emission; therefore, the service life of the LED package is rather long, and no idling time is required. In addition, the LED package has advantages of high responsive speed, small volume, little consumption of electricity, low degree of pollution (no mercury contained), great reliability, adaptation of mass production, and so on. Thus, applications of the LED package are extensive. Recently, light emitting efficiency of the LED package is continuously increasing, such that conventional fluorescent lamps and incandescent bulbs tend to be gradually replaced by a white LED package serving as a light source of a scanner, a back light source of a liquid crystal display screen, or an illuminator, for example. Common white LED packages according to the related art mainly include following types:
1. The white light is produced by using a blue LED chip and yellow fluorescent powder. Here, after the yellow inorganic fluorescent powder is irradiated by blue light emitted by the blue LED chip, yellow fluorescent light can be emitted. After the yellow fluorescent light is mixed with the original blue light, a two-wavelength-band white light can be generated. The white LED package has a plurality of blue LED chips electrically connected to one another in parallel. Nonetheless, it is difficult to perform an electrical test individually on the blue LED chips electrically connected to one another in parallel, and thereby manufacturing costs are raised. Besides, when one or more of the blue LED chips in the white LED package are damaged, a loaded current of the other blue LED chips connected in parallel to the damaged blue LED chips is increased, such that the other blue LED chips connected in parallel to the damaged blue LED chips are apt to be damaged.
2. The white light is produced by simultaneously using a red LED chip, a blue LED chip, and a green LED chip. In this kind of white LED package, a plurality of single-colored LED chips must be employed at the same time, and the single-colored LED chips exemplarily including the red LED chip, the blue LED chip, and the green LED chip are adapted to different driving voltages. Therefore, the red LED chip, the blue LED chip, and the green LED chip are connected in parallel by sharing the cathode or the anode. When one or more of the single-colored LED chips in the white LED package are damaged, a loaded current of the other single-colored LED chips connected in parallel to the damaged single-colored LED chips is increased, such that the other single-colored LED chips connected in parallel to the damaged single-colored LED chips are apt to be damaged.